There's still the tftp->ipxe->http->??? path. TFTP only needs to serve a 300kb file which can then switch to more robust transport like http for the kernel/OS

You could bypass that by shipping iPXE on USB tho

On metal you also commonly have a BMC so generally that lets you attach an ISO or other storage you can boot from to bypass UEFI primitive PXE. This is probably the biggest one--use BMC functionality instead of UEFI PXE

At home, I use JetKVM or GL.iNet Comet network KVM to bootstrap commodity hardware without BMC (by attaching an ISO). Probably could make a cheap commodity device with Raspberry Pi Zero that does that same thing at lower cost although at that point you're back to "just use USB storage"